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    <center>Scilab Function</center>
    <div align="right">Last update : 04/05/2005</div>
    <p>
      <b>grayplot</b> - 2D plot of a surface using
  colors</p>
    <h3>
      <font color="blue">Calling Sequence</font>
    </h3>
    <dl>
      <dd>
        <tt>grayplot(x,y,z,[strf,rect,nax])</tt>
      </dd>
      <dd>
        <tt>grayplot(x,y,z,&lt;opt_args&gt;)</tt>
      </dd>
    </dl>
    <h3>
      <font color="blue">Parameters</font>
    </h3>
    <ul>
      <li>
        <tt>
          <b>x,y</b>
        </tt>: real row vectors of size n1 and n2.</li>
      <li>
        <tt>
          <b>z</b>
        </tt>: real matrix of size (n1,n2). <tt>
          <b>z(i,j)</b>
        </tt> is the value
          of the surface at the point (x(i),y(j)).</li>
      <li>
        <tt>
          <b>&lt;opt_args&gt;</b>
        </tt>: This represents a sequence of statements <tt>
          <b>key1=value1,
          key2=value2</b>
        </tt>,... where <tt>
          <b>key1</b>
        </tt>,
          <tt>
          <b>key2,...</b>
        </tt> can be one of the following: rect, nax, strf
          or axesflag and frameflag (see <tt>
          <b>plot2d</b>
        </tt> and
          <tt>
          <b>plot2d_old_version</b>
        </tt>).</li>
      <li>
        <tt>
          <b>strf,rect,nax</b>
        </tt>: see <tt>
          <b>plot2d</b>
        </tt>.</li>
    </ul>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
      <tt>
        <b>grayplot</b>
      </tt> makes a 2D plot of the surface given by
    <tt>
        <b>z</b>
      </tt> on a grid defined by <tt>
        <b>x</b>
      </tt> and <tt>
        <b>y</b>
      </tt>.
    Each rectangle on the grid is filled with a gray or color level depending
    on the average value of <tt>
        <b>z</b>
      </tt> on the corners of the
    rectangle.</p>
    <p>Enter the command <tt>
        <b>grayplot()</b>
      </tt> to see a demo.</p>
    <h3>
      <font color="blue">Examples</font>
    </h3>
    <pre>

x=-10:10; y=-10:10;m =rand(21,21);
grayplot(x,y,m,rect=[-20,-20,20,20])
t=-%pi:0.1:%pi; m=sin(t)'*cos(t);
clf()
grayplot(t,t,m)
 
  </pre>
    <h3>
      <font color="blue">See Also</font>
    </h3>
    <p>
      <a href="fgrayplot.htm">
        <tt>
          <b>fgrayplot</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="plot2d.htm">
        <tt>
          <b>plot2d</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="Sgrayplot.htm">
        <tt>
          <b>Sgrayplot</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="Sfgrayplot.htm">
        <tt>
          <b>Sfgrayplot</b>
        </tt>
      </a>,&nbsp;&nbsp;</p>
    <h3>
      <font color="blue">Author</font>
    </h3>
    <p>J.Ph.C.</p>
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